Climate-Controlled Cabs Contribute To Equipment’s Ergonomic Design

Climate control in Jarraff's tree trimmer cabs is based on a conceptual redesign of hydraulic HVAC systems.

The fundamental goal of ergonomic design, now more than a 75-year-old scientific discipline, can perhaps be reduced to a single principle: minimize factors that cause fatigue to improve operator well-being and, consequently, optimize performance. Industry-leading manufacturers of off-road heavy equipment must certainly prioritize safety through features such as FOPS/ROPS- and OPS-certification in their cab designs.

But operators also want a cab to be more than just a sturdy suit of armor. They need it to be user-friendly and comfortable. For most North American operators, cab comfort includes climate control.

Jarraff Industries of St. Peter, Minnesota, makers of Jarraff all-terrain tree trimmers and Geo-Boy brush cutters, was able to create what may be the safest, most ergonomic and comfortable cabs of any machines of their kind. In large part, Jarraff was able to accomplish this by listening closely to its customers.

Heidi Boyum, president of Jarraff Industries, says input from operators has always played an important role in Jarraff’s upgrades and designs. Jarraff collects operator feedback a variety of ways, including reporting from its sales force and from customer service calls, to interaction at trade shows. “Sometimes it comes in the form of a verbal wish list or a comment that, ‘This would be nice to have,'” Boyum says.

Operator input has driven several upgrades over the years, such as joystick pilot controls, changes to propulsion design, and even the location and the orientation of the cab.

Jarraff customers range from landowners and utility contractors to utility companies, municipalities and the U.S. Fish and Wildlife Service. End-users work in every region of the continent, representing the gamut of North America’s climates – from heat and humidity to cold and wet, and from full exposure to the sun on breezeless days to punishing wind-driven debris or sudden, violent storms.

For climate control, Jarraff Industries turned to improved hydraulically-driven HVAC technology. A self-contained version of this complete concept redesign in hydraulically powered HVAC takes up only as much space in the cab wall as a small window air conditioning unit.

Image Courtesy Of Kenway Engineering

“We learned that, from a North American operator’s standpoint, a climate-controlled cab is a highly valued design feature,” Boyum explains.

For this industry’s machinery, especially tree trimmer machines with cabs that move independently of their carriers, climate control was problematic. “Originally the cab was a cage-style design with no climate-control options,” Boyum says. “That was because the cab needs to be non-conductive, insulating it from the boom as a precaution against electrical strikes.” Also, the independent motion of the cab introduces additional parts and more wear points for conventional split-unit, or radiator-based, heating, ventilating and air conditioning systems (HVAC). These weaknesses were incompatible with Jarraff’s manufacturing goals, Boyum says. But that was before technical innovations in HVAC were introduced to the off-road equipment industry, permitting Jarraff engineers to address the problem without compromise.

“We determined with the new technology we could indeed make the cab not only safe for the operator, but much more comfortable,” Boyum says. After thorough testing of the new technologies, Jarraff chose the Kenway 9067 Series unit to be its OEM HVAC solution.

The Kenway 9067 runs off just a tiny flow of a rig’s own hydraulic system and can be installed as either a split unit or as a fully self-contained system about the size of a small window air conditioner. The self-contained unit configuration preserves Jarraff’s need to isolate the tree trimmer’s cab from its boom and eliminates swivel-induced routing complications. A Kenway 9067 Series installation requires only a rectangular opening in the cab wall, four hose connections and a single electrical hookup.

It’s not the first time hydraulic HVAC designs have been introduced to the heavy-equipment industry. In fact, Kenway Engineering itself has been designing and building them for heavy-duty, off-road equipment for over 20 years. Unlike the Kenway 9067 Series, however, legacy hydraulic HVAC designs were notoriously inefficient and short-lived. The Kenway 9067 is a complete concept redesign that eliminates all major contributors to premature failure of the older systems. The new hydraulic HVAC design began with a part-by-part analysis organized by Ken Detloff, co-owner of Kenway Engineering, and Rey Carlson, Kenway’s chief engineer and service technician. They examined which parts of their existing units came back for repairs to determine common points of wear that could be eliminated.

“We had two goals in the beginning,” Carlson explains. “The first was to make a much more reliable system. We wanted our units to outlive the rigs they went into. Other systems were susceptible to the side torque the motor bearing had to endure. Once we eliminated that side torque with an outboard bearing assembly, we eliminated problems with seals wearing out and bearing run-out. That took care of a lot of problems.”

The resulting Kenway 9067 design eliminated all major contributors to premature failure. “Warranties on hydraulic HVAC used to bite a manufacturer,” Carlson says. “But this one, there just aren’t any repair calls for it. We have parts for it, but we haven’t had a need to send any out.”

Kenway’s other goal from the start, Carlson says, was to boost performance. “Previous hydraulic systems were underachievers. We needed to create an overachiever.” The result is an additional benefit of the Kenway 9067 – it can heat or cool equally well at idle or under load, on a flow as little as 8 gph.

By comparison, the engine of a rig with a traditional pressurized radiator would have to be running fast and hard to produce results equal to a Kenway 9067 at idle. This means the user saves on fuel costs, since operators will not be revving the engine simply to heat or cool the cab environment.

Kenway can upgrade any existing machinery cab with its 9067 system. Its control system can be installed in the operator’s panel and made to match the cab manufacturer’s design scheme. Or it can be installed, as in Jarraff’s cabs, where the HVAC control system is a separate, stand-alone type of Kenway’s design.

Boyum adds, “Jarraff and Geo-Boy operators and owners alike appreciate how our current cab design holds up to the elements. And now operators have the complete package – comfortable seating and user-friendly ergonomics in a climate-controlled cab.”